gatherenum – A crossover of align* and enumerate

This pack­age (ab)uses the in­line enu­mer­a­tion ca­pa­bil­i­ties of
en­u­mitem to add a “dis­played”
enu­mer­a­tion mode, trig­gered by adding ‘gath­ered’ to the
key-value op­tion list of the enu­mer­ate
en­vi­ron­ment. The end re­sult is sim­i­lar to a reg­u­lar
enu­mer­ate en­vi­ron­ment wrapped in
a mul­ti­cols en­vi­ron­ment, with the
fol­low­ing ad­van­tages:

Gathered enu­mer­ate can pack items de­pend­ing on their ac­tual
width rather than a fixed, con­stant num­ber per line.

Gathered enu­mer­a­tion fills items in a line-ma­jor or­der (in­stead of
col­umn-ma­jor or­der), which my stu­dents found less con­fus­ing. YMMV.